This invention relates to ink jet printheads. More particularly, this invention relates to a nozzle arrangement that includes a thermal actuator for an ink jet printhead
Applicant has invented an ink jet printhead that is capable of generating text and images at a resolution of up to 1600 dpi.
In order to achieve this, the Applicant has made extensive use of micro electro-mechanical systems technology. In particular, the Applicant has developed integrated circuit fabrication techniques suitable for the manufacture of such printheads.
As a result of the fabrication techniques developed by the Applicant, it has become possible for the Applicant to fabricate printheads that contain up to 84000 nozzle arrangements. In most of these embodiments, each nozzle arrangement includes one or more moving components which act on ink in a nozzle chamber to eject that ink from the nozzle chamber.
Applicant has spent a substantial amount of time and effort in developing a suitable actuator to drive these moving components. Applicant has found that significant problems exist with respect to prior art actuators, such as those which incorporate a buckle plate. The buckle plate mechanism is based on the principle of the buckling of a member in order to achieve rapid enough movement in one direction for the creation of an ink drop and subsequent movement in an opposite direction to separate that ink drop from a body of ink within a nozzle chamber. In order to achieve this, the buckle plate is fast with a substrate at its periphery. The buckle plate is then heated and the resultant expansion results in the buckle plate xe2x80x9cpopping outxe2x80x9d to accommodate this expansion. This xe2x80x9cpoppingxe2x80x9d movement is used to achieve drop ejection. Upon cooling of the buckle plate, the buckle plate returns to its original configuration to create a xe2x80x9csuck backxe2x80x9d effect, thereby facilitating the separation of the ink drop from the remainder of the ink in the nozzle chamber.
Applicant has found through extensive research and development, that the buckle plate uses too much energy in order to be utilized in a printhead of the type described above. In particular, the Applicant has found that the amount of energy required to achieve the buckling of the plate is simply excessive when applied to each of the many thousands of nozzle arrangements required to achieve a pagewidth printhead capable of the high resolution mentioned above.
Accordingly, the Applicant has conceived the invention in order to achieve an actuator which can be manufactured according to an integrated circuit fabrication technique and which is efficient enough to be used in such a printhead.
According to a first aspect of the invention, there is provided a nozzle arrangement for an ink jet printhead, the nozzle arrangement comprising
a substrate; and
an actuator that is arranged on the substrate for ejecting ink from a nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member having an anchored portion that is anchored to the substrate and a working portion that is movable with respect to the substrate, the, or each, actuating member incorporating a material having a coefficient of thermal expansion which is such that, when heated, the, or each, working portion is capable of expansion and consequent movement sufficient to perform work; and
at least one heating device that is positioned in, and in contact with, the, or each respective, working portion to heat the, or each, working portion.
According to a second aspect of the invention, there is provided a nozzle arrangement for an ink jet printhead, the nozzle arrangement comprising
a substrate; and
an actuator that is arranged on the substrate for ejecting ink from a nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member having an anchored portion that is anchored to the substrate and an end portion that is movable with respect to the substrate, the, or each, actuating member incorporating a material having a coefficient of thermal expansion which is such that, when heated, the, or each, actuating member is capable of expansion with consequent movement of the end portion being sufficient to perform work; and
a heating device that is operatively positioned with respect to the, or each, actuating member to heat the, or each, actuating member.
According to a third aspect of the invention, there is provided an ink jet printhead that comprises
a substrate; and
at least one nozzle arrangement that is arranged on the substrate, the, or each, nozzle arrangement comprising
an actuator that is arranged on the substrate for ejecting ink from a nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member having an anchored portion that is anchored to the substrate and a working portion that is movable with respect to the substrate, the, or each, actuating member incorporating a material having a coefficient of thermal expansion which is such that, when heated, the, or each, working portion is capable of expansion and consequent movement sufficient to perform work; and
at least one heating device that is positioned in, and in contact with, the, or each respective, working portion to heat the working portion.
According to a fourth aspect of the invention, there is provided an ink jet printhead that comprises
a substrate; and
at least one nozzle arrangement that is arranged on the substrate, the, or each, nozzle arrangement comprising
an actuator that is arranged on the substrate for ejecting ink from a nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member having an anchored portion that is anchored to the substrate and an end portion that is movable with respect to the substrate, the, or each, actuating member incorporating a material having a coefficient of thermal expansion which is such that, when heated, the, or each, actuating member is capable of expansion with consequent movement of the end portion being sufficient to perform work; and
a heating device that is operatively positioned with respect to the, or each, actuating member to heat the, or each, actuating member.